Considering the present state and future projections for sulfur consumption, large amounts of excess sulfur, e.g., 80 Mt worldwide in the next twenty years, might be accumulated in many areas of the world. For example, supply of recovered sulfur is already outpacing the demand for sulfur in energy-rich regions such as Alberta, Canada, and west Kazakhstan. Such outpacing of the supply of sulfur relative to the demand for sulfur is expected to occur globally and will cause the need for large scale storage of waste sulfur or sulfur products.
However, stockpiles of elemental sulfur are unsafe. For example, sulfur dust can settle near storage sites and acidify the surrounding soil. Acidification and the metals leached from the soil and transported to other locations can cause significant environmental damage, such as drastic changes in local water and soil pH. In addition, long-term sulfur storage poses significant risk of ignition and sulfur fires, as well as the potential for bacterial degradation and oxidation.
Despite such risks and concerns, suitable solutions to safe, e.g., low solubility in water, noncombustible, and reasonably resistant to bacterial digestion, long-term storage of sulfur are not currently available. For example, one method essentially provides a disposal strategy wherein sour gases, i.e., gas mixtures including substantial amounts of acidic gases like hydrogen sulfide (H2S), sulfur dioxide (SO2), sulfur trioxide (SO3), and carbon dioxide (CO2), are re-injected underground. However, this method poses environmental risks because these sour gases might escape over time and be reintroduced into the environment causing ecological damage. For example, acid gas can react with well plugs that are typically made of concrete and escape over time. Other forms of leakage are possible insofar as reservoirs can develop leaks over time.